Number of processes started by IPyParallel clusters

A lot of users seem to be surprised by the number of processes that are started as part of an IPyParallel cluster. In my testing, we seem to start 2 processes per engine (the engine itself and the nanny), an mpiexec process in case of MPI-Launcher, and 9 processes for the controller. The number of controller processes seem to be higher than expected (5 vs 9) based on: https://ipyparallel.readthedocs.io/en/latest/reference/connections.html#all-connections.

1. Is this in line with what you expect (9 processes)? If so, is this a documentation issue that we could fix? If not, is this a bug that needs to be fixed?
2. Is there a way to reduce the number of processes required in general across the board, in particular for the controller?
3. Can we improve the documentation on this in general?